I'm currently using an expander from Ubit with no success.
I hope you are trying that in Linux, because Windows does not support more than 8 same cards.
It’s is not true that windows can not support more than 8 GPUs. I myself running 10 GPUs with Windows 10 for sometime. All are gtx 1070s. You probably have to update the windows current updates. It should work. I also run couple of 12 GPU rigs with ethos which is also very good and stable.
Correct - Windows had an update around the end of last year that allows more than 8 NV GPUs now. There's no more limitation.